Following the intracellular recording of bipolar cell responses in salamander retina, each unit was injected with horseradish peroxidase and a histochemical staining used to identify it at the level of the electron microscope. It was in this way established that either center-depolarizing or center-hyperpolarizing bipolar cells made both ribbon and basal junctions with the receptors. Therefore, no structural correlates of the sign of synaptic transmission could be discerned.